Endoscope flexible tube and method of manufacturing endoscope flexible tube

ABSTRACT

An endoscope flexible tube according to the present invention includes: a spiral tube configured such that a belt-like plate is spirally wound; an inner cylindrical member disposed inside an end part of the spiral tube; and an outer cylindrical member that is disposed outside the end part of the spiral tube, and holds the end part of the spiral tube between the inner cylindrical member and the outer cylindrical member. The inner cylindrical member has an outer diameter that is set larger than an inner diameter of the spiral tube, and the end part of the spiral tube is deformed to enlarge the inner diameter of the end part, and is externally fitted to the inner cylindrical member.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of PCT/JP2016/059131filed on Mar. 23, 2016 and claims benefit of Japanese Application No.2015-154274 filed in Japan on Aug. 4, 2015, the entire contents of whichare incorporated herein by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an endoscope flexible tube that is insertedinto an endoscope insertion section in order to realize flexibility ofthe endoscope insertion section and a method of manufacturing anendoscope flexible tube.

2. Description of the Related Art

An endoscope having an elongated tubular insertion section has beenconventionally widely used, for example, in a medical field and anindustrial field. Among the endoscopes, a medical endoscope used in themedical field is configured in such a manner that a flexible insertionsection can be inserted into a body cavity of a subject such as a livingbody to allow for observation of organs or the like, or various kinds oftreatment can be performed on the organs or the like with use oftreatment instruments inserted into a treatment instrument insertionchannel provided in the endoscope, as necessary. In addition, anindustrial endoscope used in the industrial field is configured in sucha manner that a flexible insertion section can be inserted into anobject, for example, an apparatus such as a jet engine or an inside ofequipment such as factory piping to allow for observation, inspection ofa state and the like inside the object, for example, damage andcorrosion.

The insertion section of the endoscope of the kind includes a distal endrigid portion, a bending portion, and a flexible tube that are connectedin order from distal end side of the insertion section, and proximal endside of the flexible tube is coupled and fixed to a distal end of anoperation section. Here, the flexible tube typically has a three-layerstructure of a metal flex layer (a spiral tube), a metal braid layer (amesh tube), and an elastomer outer resin layer (an outer skin). Inaddition, an inner pipe sleeve is disposed inside the flex layer of theflexible tube and an outer pipe sleeve is disposed on outer diameterside of the flex layer, at a coupling fixing portion between theproximal end side of the flexible tube and the distal end side of theoperation section. This causes the flexible tube to be held between theinner pipe sleeve and the outer pipe sleeve. The inner pipe sleeve hasan outer diameter smaller than an inner diameter of the flex layer. Inthe state, the outer pipe sleeve is swaged to fix the flexible tube. Theendoscope flexible tube having such a configuration has been disclosedby, for example, Japanese Patent Application Laid-Open Publication No.2009-153714, and has been widely practiced.

In contrast, an endoscope flexible tube disclosed by, for example,Japanese Patent Application Laid-Open Publication No. 2009-261645 has aconfiguration in which the flexible tube and the bending portion arearranged in contact with each other and a contact portion is welded tocouple the flexible tube to the bending portion.

SUMMARY OF THE INVENTION

An endoscope flexible tube according to an aspect of the presentinvention includes: a spiral tube configured such that a belt-like plateis spirally wound; an inner cylindrical member disposed inside an endpart of the spiral tube; and an outer cylindrical member that isdisposed outside the end part of the spiral tube, and holds the end partof the spiral tube between the inner cylindrical member and the outercylindrical member. The inner cylindrical member has an outer diameterthat is set larger than an inner diameter of the spiral tube, and theend part of the spiral tube is deformed to enlarge the inner diameter ofthe end part, and is externally fitted to the inner cylindrical member.

In addition, a method of manufacturing an endoscope flexible tubeaccording to an aspect of the present invention is a method ofmanufacturing an endoscope flexible tube that includes: a spiral tubeconfigured such that a belt-like plate is spirally wound; an innercylindrical member disposed inside an end part of the spiral tube; andan outer cylindrical member that is disposed outside the end part of thespiral tube, and holds the end part of the spiral tube between the innercylindrical member and the outer cylindrical member. The methodincludes: deforming the end part of the spiral tube to enlarge an innerdiameter of the end part to a size that is larger than an outer diameterof the inner cylindrical member and is smaller than an inner diameter ofthe outer cylindrical member; externally fitting the end part of thespiral tube to the inner cylindrical member; and plastically deformingthe outer cylindrical member toward the end part of the spiral tube tohold the end part of the spiral tube between the outer cylindricalmember and the inner cylindrical member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an entire configuration of anendoscope to which an endoscope flexible tube according to a firstembodiment of the present invention is applied;

FIG. 2 is a main-part exploded cross-sectional diagram illustrating aportion of components (a three-layered tube and an inner pipe sleeve) onproximal end side of an endoscope flexible tube according to a secondembodiment of the present invention, in an exploded manner;

FIG. 3 is a cross-sectional diagram illustrating a state in which thethree-layered tube and the inner pipe sleeve that are in an explodedstate in FIG. 2 are assembled;

FIG. 4 is a cross-sectional diagram illustrating a state in which an endpart of the three-layered tube and an end part of the inner pipe sleeveare inserted into an outer pipe sleeve, in the endoscope flexible tubeaccording to the first embodiment of the present invention;

FIG. 5 is a cross-sectional diagram illustrating a state in which theend part of the three-layered tube and the end part of the inner pipesleeve have been assembled to the outer pipe sleeve (a state in whichswaging work has been completed), in the endoscope flexible tubeaccording to the first embodiment of the present invention;

FIG. 6 is a main-part exploded cross-sectional diagram illustrating aportion of components on the proximal end side of the endoscope flexibletube according to a second embodiment of the present invention, andillustrating the three-layered tube and the inner pipe sleeve in anexploded manner (corresponding to FIG. 2 of the first embodiment);

FIG. 7 is a cross-sectional diagram illustrating a state in which thethree-layered tube and the inner pipe sleeve that are in an explodedstate in FIG. 6 are assembled (corresponding to FIG. 3 of the firstembodiment);

FIG. 8 is a cross-sectional diagram illustrating a state in which an endpart of the three-layered tube and an end part of the inner pipe sleeveare inserted into an outer pipe sleeve, in the endoscope flexible tubeaccording to the second embodiment of the present invention(corresponding to FIG. 4 of the first embodiment); and

FIG. 9 is a cross-sectional diagram illustrating a state in which theend part of the three-layered tube and the end part of the inner pipesleeve have been assembled to the outer pipe sleeve (a state in whichswaging work has been completed), in the endoscope flexible tubeaccording to the second embodiment of the present invention(corresponding to FIG. 5 of the first embodiment).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

The present invention is described below based on illustratedembodiments. The respective drawings used in the following descriptionare schematic illustration, and dimension relationship, scale sizes, andthe like of respective members may be varied in illustration for eachcomponent in order to illustrate the components with respectiverecognizable sizes in the drawings. Therefore, the present invention isnot limited to illustrated forms, in terms of the number of components,shapes of the respective components, a size ratio of the components,relative positional relationship between the components, and the likethat are illustrated in the respective drawings.

First Embodiment

FIG. 1 is a perspective view illustrating an entire configuration of anendoscope to which an endoscope flexible tube according to a firstembodiment of the present invention is applied.

Before detailed description of the endoscope flexible tube according tothe first embodiment of the present invention, the entire configurationof the endoscope to which the endoscope flexible tube is applied isfirst described below with reference to FIG. 1.

An endoscope 1 to which the endoscope flexible tube (hereinafter, simplyreferred to as the flexible tube) according to the first embodiment ofthe present invention is applied mainly includes an insertion section 2,an operation section 3, and a universal cable 4, as illustrated in FIG.1.

Although not illustrated, a light guide cable, an air/water feedingtube, various signal lines, and an internal structure such as atreatment instrument insertion channel are inserted into the insertionsection 2, the operation section 3, and the universal cable 4.

The insertion section 2 is a component that is so formed in an elongatedflexible tubular shape as a whole as to be insertable into a body cavityor the like. The insertion section 2 includes a distal end portion 5, abending portion 6, and a flexible tube 7 in order from distal end sideof the insertion section 2.

The distal end portion 5 includes, on a distal end surface, anobservation window, an illumination window, a treatment instrumentopening, a cleaning nozzle, etc. (not illustrated). In addition, anobservation optical system, an image pickup device, etc. (notillustrated) are provided inside the distal end portion 5. Theobservation optical system and the image pickup device are connected torear side of the observation window. Various kinds of signal lines andother lines are extended backward from the image pickup device. Further,a distal end of the light guide cable (not illustrated) is connected torear side of the illumination window, inside the distal end portion 5.The light guide cable transmits, to the distal end portion 5,illumination light that is emitted from an unillustrated illuminationapparatus. Likewise, a distal end of the air/water feeding tube (notillustrated) is connected to the cleaning nozzle, inside the distal endportion 5. The air/water feeding tube is extended from an unillustratedair/water feeding apparatus, and passes through the insertion section 2,the operation section 3, and the universal cable 4 and reaches thedistal end portion 5. Furthermore, a distal end of the treatmentinstrument insertion channel is connected to rear side of the treatmentinstrument opening, inside the distal end portion 5.

The bending portion 6 is a component that makes a predetermined range ofthe distal end side of the insertion section 2 bendable. It is assumedthat the bending portion 6 itself has a configuration similar to abending portion of an endoscope that is in practical use generally andwidely spread, and the description of the configuration is omitted.

The flexible tube 7 is a tubular member having flexibility as a whole.One end on distal end side of the flexible tube 7 is connected to aproximal end of the bending portion 6, and the other end on proximal endof the flexible tube 7 is connected to a distal end of the operationsection 3. Note that the detailed configuration of the flexible tube 7is described later.

The operation section 3 is a housing section that has an internal space.The proximal end of the insertion section 2 is connected to theoperation section 3. A plurality of operation members and the like areprovided on an outer surface of the operation section 3. The variouskinds of signal lines, the light guide, an air/water feeding conduit,and the like that are extended from the insertion section 2 are insertedinto the operation section 3, and an electric substrate, or the like onwhich an electronic circuit and other parts are mounted is disposedinside the operation section 3. The electronic circuit receives inputsignals respectively from the plurality of operation members. Examplesof the plurality of operation members may include a bending lever 9 thatis used to perform bending operation. Note that a connection sitebetween the flexible tube 7 and the operation section 3 is covered witha bend preventing portion 8 and is thus protected from outside.

The universal cable 4 is a tubular cable that is extended from theoperation section 3, and the various kinds of signal lines, the lightguide, the various kinds of air/water feeding conduits, and the like areinserted into the universal cable 4. A connector portion 10 is connectedto distal end side of the universal cable 4. The connector portion 10 isa connection member that is provided to be detachable from anunillustrated control unit and secures electrical and mechanicalconnection between the endoscope 1 and the control unit.

Note that it is assumed that the endoscope 1 has configurationssubstantially similar to configurations of the endoscope that is inpractical use generally and widely spread in terms of more detailedconfiguration and other components, and the detailed description andillustration of the more detailed configuration and the other componentsare accordingly omitted.

Next, the detailed configuration of the endoscope flexible tube 7according to the present embodiment is described below with reference toFIG. 2 to FIG. 5. FIG. 2 to FIG. 5 are vertical cross-sectional diagramseach illustrating the configuration on the proximal end side of theendoscope flexible tube according to the present embodiment, in asimplified manner. Among the drawings, FIG. 2 is a diagram illustratinga portion of components on the proximal end side of the endoscopeflexible tube according to the present embodiment, and is a main-partexploded cross-sectional diagram illustrating a three-layered tube andan inner pipe sleeve in an exploded manner. FIG. 3 is a diagramillustrating a state in which the three-layered tube and the inner pipesleeve that are in an exploded state in FIG. 2 are assembled. FIG. 4 isa diagram illustrating a state in which an end part of the three-layeredtube and an end part of the inner pipe sleeve are inserted into an outerpipe sleeve, in the endoscope flexible tube according to the presentembodiment. FIG. 5 is a diagram illustrating a state in which the endpart of the three-layered tube and the end part of the inner pipe sleevehave been assembled to the outer pipe sleeve (a state in which swagingwork has been completed), in the endoscope flexible tube according tothe present embodiment.

Note that FIG. 2 to FIG. 5 are diagrams each illustrating an internalconfiguration of a site denoted by a reference sign [A] of FIG. 1,namely, a configuration near a coupling site between the proximal end ofthe endoscope flexible tube and the distal end of the operation section,in an enlarged manner.

As illustrated in FIG. 2 and FIG. 3, a main part of the flexible tube 7has a three-layer structure that includes a spiral tube 11 serving as aflex layer, a mesh tube 12 serving as a braid layer, and an outer skin13 serving as an outer resin layer.

The spiral tube 11 serving as the flex layer is a structure obtained byspirally winding a thin belt-like plate into a substantially circulartube shape. The band-like plate is formed of a metal material such asstainless steel.

The mesh tube 12 serving as the braid layer is a structure that isobtained by forming a metal mesh member into a substantially circulartube shape, and is so disposed as to cover an outer surface (as to be incontact with an outer periphery) of the spiral tube 11. The metal meshmember is obtained by braiding, into a net shape, strand bundles eachincluding a plurality of strands. The strands are each made of a metalsuch as stainless steel.

The outer skin 13 serving as the outer resin layer is a structureobtained by forming a flexible resin material such as elastomer into asubstantially circular tube shape. The outer skin 13 is so disposed asto cover an outer surface (as to be in contact with an outer periphery)of the mesh tube 12.

Here, the tubular member having the three-layer structure that includesthe spiral tube 11, the mesh tube 12, and the outer skin 13 is referredto as a three-layered tube 20. The flexible tube 7 according to thepresent embodiment mainly includes the three-layered tube 20, an innerpipe sleeve 14 that is an inner cylindrical member, and an outer pipesleeve 15 that is an outer cylindrical member (see FIG. 5).

The inner pipe sleeve 14 is fitted to an inside of an end part 21 on theproximal end side of the three-layered tube 20. The inner pipe sleeve 14is provided in order to bundle the end part 21 of the three-layered tube20. In addition, the inner pipe sleeve 14 and the outer pipe sleeve 15are connection parts to couple a proximal end portion of the flexibletube 7 to the distal end portion of the operation section 3, asdescribed later.

The inner pipe sleeve 14 is a structure that includes a cylinder portion14 b and an outward flange portion 14 a. The cylinder portion 14 b isformed of, for example, a metal material in a cylindrical shape as awhole. The outward flange portion 14 a is provided at one end part ofthe cylinder portion 14 b.

Here, a form of the three-layered tube 20 before the flexible tube 7 isassembled is as illustrated in FIG. 2. In the state illustrated in FIG.2, the three-layered tube 20 is in an unloaded state. The state isregarded as a normal state. When the three-layered tube 20 is in thenormal state, an inner diameter (see a reference sign D1 in FIG. 2) ofthe spiral tube 11 is substantially fixed from the distal end to theproximal end. Further, in the normal state, the inner diameter (see areference sign D1 in FIG. 2) of the end part 21 of the three-layeredtube 20 (the spiral tube 11) and an inner diameter (see a reference signD2 in FIG. 2) of the inner pipe sleeve 14 (the inner cylindrical member)are made substantially equal to each other (D1≈D2).

When the inner pipe sleeve 14 (the inner cylindrical member) is disposedinside the end part 21 of the three-layered tube 20 in the state of FIG.2, a portion of the flexible tube 7 is assembled in a form illustratedin FIG. 3. To do so, the cylinder portion 14 b of the inner pipe sleeve14 is fitted into the end part 21 of the three-layered tube 20 while thediameter of the end part 21 of the three-layered tube 20 is enlarged toa size larger than an outer periphery of the cylinder portion 14 b ofthe inner pipe sleeve 14 (in other words, force in an arrow B directionof FIG. 2 is applied to the end part 21 to enlarge the diameter). Here,the site at which the diameter of the end part 21 of the three-layeredtube 20 is enlarged is denoted by a reference sign 11 a in FIG. 3. Inthe following, the site denoted by the reference sign 11 a is referredto as an enlarged-diameter part 11 a.

At this time, the end part 21 of the three-layered tube 20 is positionedin an axial direction (an insertion direction) by the outward flangeportion 14 a of the inner pipe sleeve 14. Application of the enlargingforce in the arrow B direction to the end part 21 of the three-layeredtube 20 is released after fitting of the inner pipe sleeve 14 to thethree-layered tube 20 is completed. This brings the end part 21 of thethree-layered tube 20 (the spiral tube 11) into contact with the outerperiphery of the cylinder portion 14 b of the inner pipe sleeve 14 bybiasing force of the spiral tube 11. At this time, the enlarged-diameterstate of the end part 21 of the three-layered tube 20 (the spiral tube11) is maintained by the cylinder portion 14 b of the inner pipe sleeve14. The three-layered tube 20 and the inner pipe sleeve 14 are assembledin such a manner, which causes the portion of the flexible tube 7according to the present embodiment to be assembled in the formillustrated in FIG. 3.

In the state illustrated in FIG. 3, the inner pipe sleeve 14 (the innercylindrical member) is disposed inside the end part 21 of thethree-layered tube 20 (the spiral tube 11). At this time, the diameterof the end part 21 of the three-layered tube 20 (the spiral tube 11) isenlarged at the enlarged-diameter part 11 a. Therefore, the inner pipesleeve 14 is disposed inside the end part 21 of the three-layered tube20 (the spiral tube 11) such that the diameter of the end part 21 of thethree-layered tube 20 (the spiral tube 11) becomes larger than adiameter of a part 22 that is different from the end part 21 of thethree-layered tube 20 (the spiral tube 11).

Note that, as illustrated in FIG. 3, the end part 21 of thethree-layered tube 20 (the spiral tube 11) refers to a part at which theinner periphery of the spiral tube 11 is in contact with the outerperiphery of the inner pipe sleeve 14 in the state in which the innerpipe sleeve 14 is assembled to the three-layered tube 20 (in the stateof FIG. 3). In addition, the part 22 that is different from the end part21 of the three-layered tube 20 (the spiral tube 11) refers to a part atwhich the inner periphery of the spiral tube 11 is not in contact withthe outer periphery of the inner pipe sleeve 14 in the same state.

Here, a reference sign D1A illustrated in FIG. 3 indicates an innerdiameter of the enlarged-diameter part 11 a in the end part 21 of thethree-layered tube 20 (the spiral tube 11). Further, a reference sign D1illustrated in FIG. 3 indicates an inner diameter of the part 22 that isdifferent from the end part 21 of the three-layered tube 20 (the spiraltube 11) (in the normal state of FIG. 2, the inner diameter of the endpart 21 is substantially equal to the reference sign D1). In otherwords, the inner diameter D1 of the part different from the end part 21is smaller than the inner diameter D1A of the enlarged-diameter part 11a (D1<D1A). In addition, a reference sign D2 illustrated in FIG. 3indicates the inner diameter of the inner pipe sleeve 14.

In the state of FIG. 3, namely, in the state in which the portion (thethree-layered tube 20 and the inner pipe sleeve 14) of the flexible tube7 is assembled, the inner diameter (the reference sign D2 of FIG. 3) ofthe inner pipe sleeve 14 is substantially equal to (D1≈D2) or at leastlarger than (D1<D2) the inner diameter (the reference sign D1 of FIG. 3)of the part 22 that is different from the end part 21 of the spiral tube11 in the three-layered tube 20.

The portion of the flexible tube 7 (the structure in which thethree-layered tube 20 and the inner pipe sleeve 14 are assembled)configured in such a manner is connected and fixed to the outer pipesleeve 15 that is an outer cylindrical member fixed and disposed in theoperation section 3.

The outer pipe sleeve 15 is a structure that includes a cylindricalportion 15 b and an inward flange portion 15 a. The cylindrical portion15 b is formed of, for example, a metal material in a cylindrical shapeas a whole. The inward flange portion 15 a is provided at one end partof the cylindrical portion 15 b. The outer pipe sleeve 15 is disposedoutside the end part 21 of the three-layered tube 20. In this case, theend part 21 of the three-layered tube 20 is held between the outer pipesleeve 15 and the inner pipe sleeve 14. Further, in the state, namely,in the state in which the end part 21 of the three-layered tube 20 isheld between the outer pipe sleeve 15 and the inner pipe sleeve 14, theouter pipe sleeve 15 is swaged toward the end part 21 of thethree-layered tube 20 (the spiral tube 11). This causes the end part 21of the three-layered tube 20 to be held between the outer pipe sleeve 15and the inner pipe sleeve 14 and fixed.

To assemble the end part 21 of the portion of the flexible tube 7 (thestructure in which the three-layered tube 20 and the inner pipe sleeve14 are assembled) to the outer pipe sleeve 15, the structure is firstinserted into the outer pipe sleeve 15. At this time, the structure ispositioned in the axial direction (the insertion direction) by theinward flange portion 15 a of the outer pipe sleeve 15. In the state,swaging force in an arrow F direction illustrated in FIG. 4 is appliedto the cylindrical portion 15 b of the outer pipe sleeve 15. This causesa portion of the outer pipe sleeve 15 to be swaged, which results in astate illustrated in FIG. 5. As a result, the end part 21 of thethree-layered tube 20 is held between the outer pipe sleeve 15 and theinner pipe sleeve 14 and fixed.

Note that the distal end portion, namely, the site coupled to thebending portion 6, of the flexible tube 7 also has a similarconfiguration. The illustration and description of the distal endportion of the flexible tube 7 are omitted because the portion does notdirectly relate to the present embodiment.

As mentioned above, according to the above-described first embodiment,the inner pipe sleeve 14 (the inner cylindrical member) of the endoscopeflexible tube is disposed inside the end part 21 of the three-layeredtube 20 (the spiral tube 11). At this time, the inner pipe sleeve 14(the inner cylindrical member) is disposed inside the end part 21 of thethree-layered tube 20 (the spiral tube 11) such that the diameter of theend part 21 of the three-layered tube 20 (the spiral tube 11) (morespecifically, for example, the inner diameter D1 of the spiral tube 11in the normal state) becomes larger than the diameter of the part 22that is different from the end part 21 of the three-layered tube 20 (thespiral tube 11). As a result, the inner diameter D2 of the inner pipesleeve 14 (the inner cylindrical member) is substantially equal to(D1≈D2) or at least larger than (D1<D2) the inner diameter D1 of thepart 22 that is different from the end part 21 of the three-layered tube20 (the spiral tube 11).

Here, the end part 21 of the three-layered tube 20 (the spiral tube 11)is disposed while the diameter of the end part 21 is enlarged to thesize larger than the outer periphery of the inner pipe sleeve 14 (theinner cylindrical member). In addition, the end part 21 of thethree-layered tube 20 (the spiral tube 11), namely, the end part 21 ofthe spiral tube 11, the mesh tube 12, and the outer skin 13 is heldbetween the inner pipe sleeve 14 (the inner cylindrical member) and theouter pipe sleeve 15 (the outer cylindrical member) and fixed. Here, theouter pipe sleeve 15 (the outer cylindrical member) is swaged toward theend part 21 of the three-layered tube 20 (the spiral tube 11), whichfixes the end part 21.

Such a configuration allows the inner diameter D1 of the spiral tube 11to be substantially equal to the inner diameter D2 of the inner pipesleeve 14 (D1≈D2), or allows the inner diameter D2 of the inner pipesleeve 14 to be at least larger than the inner diameter D1 of the spiraltube 11 (D1<D2). This makes it possible to secure larger internal spaceof the inner pipe sleeve 14 as compared with the endoscope flexible tubehaving the conventional structure. Accordingly, it is possible to securethe storage quantity of built-in components in the internal space thatis equivalent to or larger than the storage quantity of the conventionalconfiguration.

In addition, since it is possible to make the diameter of the inner pipesleeve 14 larger than the conventional diameter, a gap between the outerpipe sleeve 15 and the inner pipe sleeve 14 is reduced, which makes itpossible to further decrease a swaging amount in swaging of the outerpipe sleeve 15. This contributes to reduction of a work load in themanufacturing process.

Second Embodiment

Next, an endoscope flexible tube according to a second embodiment of thepresent invention is described below with reference to FIG. 6 to FIG. 9.

FIG. 6 to FIG. 9 are diagrams each illustrating the second embodiment ofthe present invention. Among the drawings, FIG. 6 is a diagramillustrating a portion of components on proximal end side of theendoscope flexible tube according to the present embodiment, and is amain-part exploded cross-sectional diagram illustrating a three-layeredtube and an inner pipe sleeve in an exploded manner. FIG. 6 correspondsto FIG. 2 in the above-described first embodiment. FIG. 7 is a diagramillustrating a state in which the three-layered tube and the inner pipesleeve that are in an exploded state in FIG. 6 are assembled. FIG. 7corresponds to FIG. 3 in the above-described first embodiment. FIG. 8 isa diagram illustrating a state in which an end part of the three-layeredtube and an end part of the inner pipe sleeve are inserted into an outerpipe sleeve, in the endoscope flexible tube according to the presentembodiment. FIG. 8 corresponds to FIG. 4 in the above-described firstembodiment. FIG. 9 is a diagram illustrating a state in which the endpart of the three-layered tube and the end part of the inner pipe sleevehave been assembled to the outer pipe sleeve (a state in which swagingwork has been completed) in the endoscope flexible tube according to thepresent embodiment. FIG. 9 corresponds to FIG. 5 in the above-describedfirst embodiment.

A basic configuration according to the present embodiment issubstantially similar to the configuration of the first embodimentmentioned above. In the present embodiment, out of the components of theendoscope flexible tube, only the configuration of the three-layeredtube that includes the spiral tube, the mesh tube, and the outer skin isslightly different from the configuration in the first embodiment.Accordingly, detailed description of the components same as thecomponents in the above-described first embodiment is omitted, anddifferent portions are only described in detail below.

In the endoscope flexible tube according to the present embodiment, athree-layered tube 20A includes the spiral tube 11, the mesh tube 12,and the outer skin 13, as with the above-described first embodiment. Asillustrated in FIG. 3, however, the three-layered tube 20A according tothe present embodiment includes a certain clearance (a gap: a referencesign C1 in FIG. 6) between the spiral tube 11 and the mesh tube 12.Providing such a clearance C1 is to smoothly bend the flexible tubewithout obstacle. In other words, when the clearance C1 is providedbetween the spiral tube 11 and the mesh tube 12, it is possible toreduce friction between the spiral tube 11 and the mesh tube 12. Sincethe flexible tube is smoothly bent as the friction is smaller, handlingis facilitated and insertion property is improved advantageously.

To assemble the inner pipe sleeve 14 to the end part 21 of thethree-layered tube 20A having such a configuration, only the diameter ofthe spiral tube 11 is enlarged at the end part 21 of the three-layeredtube 20A and the inner pipe sleeve 14 is disposed inside the spiral tube11, as with the above-described first embodiment. This results in a formillustrated in FIG. 7. In the state, as mentioned above, the inner pipesleeve 14 (the inner cylindrical member) is disposed inside the end part21 of the spiral tube 11 of the three-layered tube 20A. At this time,the enlarged-diameter state (the inner diameter D1A) of the end part 21of the three-layered tube 20A (the spiral tube 11) is maintained. Thisis because the diameter of the inner pipe sleeve 14 is made larger thanthe inner diameter D1 of the end part 21 of the three-layered tube 20A(the spiral tube 11).

In other words, by the configuration, the inner pipe sleeve 14 isdisposed inside the end part 21 of the three-layered tube 20A (thespiral tube 11) such that the diameter of the end part 21 of thethree-layered tube 20A (the spiral tube 11) becomes larger than thediameter of the part 22 that is different from the end part 21 of thethree-layered tube 20A (the spiral tube 11), also in the presentembodiment. As a result, the inner diameter D2 of the inner pipe sleeve14 (the inner cylindrical member) is substantially equal to (D1≈D2) orat least larger than (D1<D2) the inner diameter D1 of the part 22different from the end part 21 of the three-layered tube 20A (the spiraltube 11).

The portion of the components of the flexible tube configured in such amanner, namely, the structure in which the three-layered tube 20A andthe inner pipe sleeve 14 are assembled is disposed inside the outer pipesleeve 15 through means similar to the means described in theabove-described first embodiment (see FIG. 8), and is swaged. Thisresults in the endoscope flexible tube having a form illustrated in FIG.9.

As mentioned above, in the present embodiment, when the inner pipesleeve 14 is assembled to the three-layered tube 20A that includes thespiral tube 11, the mesh tube 12, and the outer skin 13, the outer pipesleeve 15 is swaged while adjacent members of the inner pipe sleeve 14,the spiral tube 11, the mesh tube 12, the outer skin 13, and the outerpipe sleeve 15 that are provided in order from the inner side are incontact with and overlapped with each other, at the end part 21 of thespiral tube 11. In contrast, the clearance C1 is retained between theouter periphery of the spiral tube 11 and the inner periphery of themesh tube 12, at the part 22 that is different from the end part 21 ofthe spiral tube 11.

As mentioned above, the second embodiment makes it possible to provideeffects similar to the effects of the above-described first embodimentby configuring, similarly to the configuration of the above-describedfirst embodiment, the three-layered tube 20A that has the largeclearance between the spiral tube 11 serving as a flex layer and themesh tube 12 serving as a braid layer.

Note that the present invention is not limited to the above-describedembodiments, and various modifications and applications may beimplemented without departing from the scope of the invention as amatter of course. Further, the above-described embodiments includeinventions in various stages, and various inventions may be extractedthrough appropriate combination of the plurality of disclosedcomponents. For example, even if some components are deleted from allthe components described in the above-described embodiment, aconfiguration with the components deleted may be extracted as theinvention if such a configuration can solve a problem to be solved bythe invention and provide the effects of the invention. Further,components in different embodiments may be appropriately combined. Thepresent invention is not limited by a specific embodiment, except aslimited by the accompanying claims.

INDUSTRIAL APPLICABILITY

The present invention is applicable not only to an endoscope in amedical field but also to an endoscope in an industrial field.

What is claimed is:
 1. An endoscope flexible tube, comprising: a spiraltube configured such that a belt-like plate is spirally wound; an innercylindrical member disposed inside an end part of the spiral tube; andan outer cylindrical member that is disposed outside the end part of thespiral tube, and holds the end part of the spiral tube between the outercylindrical member and the inner cylindrical member, wherein the innercylindrical member has an outer diameter that is set larger than aninner diameter of the spiral tube, and the end part of the spiral tubeis deformed to enlarge the inner diameter of the end part, and isexternally fitted to the inner cylindrical member.
 2. The endoscopeflexible tube according to claim 1, wherein the outer cylindrical memberis plastically deformed toward the end part of the spiral tube to holdthe end part of the spiral tube between the outer cylindrical member andthe inner cylindrical member.
 3. The endoscope flexible tube accordingto claim 2, further comprising: a mesh tube disposed to be in contactwith an outer periphery of the spiral tube; and an outer skin disposedto be in contact with an outer periphery of the mesh tube, wherein anend part of the spiral tube, an end part of the mesh tube, and an endpart of the outer skin are held between the inner cylindrical member andthe outer cylindrical member and fixed.
 4. The endoscope flexible tubeaccording to claim 3, wherein the end part of the spiral tube forms aclearance between the end part and an inner periphery of the mesh tubebefore the inner diameter is enlarged.
 5. The endoscope flexible tubeaccording to claim 3, wherein the end part of the spiral tube, the endpart of the mesh tube, and the end part of the outer skin are disposedto be in contact with an outer periphery of the inner cylindrical memberwhile being enlarged in diameter.
 6. A method of manufacturing anendoscope flexible tube, the endoscope flexible tube comprising a spiraltube configured such that a belt-like plate is spirally wound, an innercylindrical member disposed inside an end part of the spiral tube, andan outer cylindrical member that is disposed outside the end part of thespiral tube and holds the end part of the spiral tube between the outercylindrical member and the inner cylindrical member, the methodcomprising: deforming the end part of the spiral tube to enlarge aninner diameter of the end part to a size that is larger than an outerdiameter of the inner cylindrical member and is smaller than an innerdiameter of the outer cylindrical member; externally fitting the endpart of the spiral tube to the inner cylindrical member; and plasticallydeforming the outer cylindrical member toward the end part of the spiraltube to hold the end part of the spiral tube between the outercylindrical member and the inner cylindrical member.